1. Technical Field
This invention is related to the field of automobile engine systems and control. More particularly, it is related to an apparatus and method to reduce the time required for a catalyst to reach a desired operating efficiency.
2. Discussion
The prior art includes a variety of conventional methods for detecting and using ionization current in a combustion chamber of an internal combustion engine. However, each of the various conventional systems suffers from a great variety of deficiencies. For example, prior art ionization current detection circuits are generally too slow and generate a current signal with low signal-to-noise ratio.
Air pollution from automobile exhaust is caused in part by hydrocarbon emission. A catalyst converter is used in an internal combustion engine to reduce these pollutants by converting the harmful materials to harmless materials. Because the catalyst converter does not operate when the temperature of the catalyst is below its operational point, around 70% of the hydrocarbon emission during the Federal Test Procedure cycle is produced during the cold start when the catalyst temperature is below its operational point. Various approaches using open loop calibration have been developed to heat up the catalyst quickly during the cold start. However, since spark retard is limited by partial burn and misfire, open loop calibration of a retard spark for a cold start is performed slowly and conservatively.